<template>
    <div class="spec-preview" @mousemove="mousemove">
        <img :src="skuImageList[defaultImgIndex]?.imgUrl" />
        <div class="event" ref="event"></div>
        <div class="big">
            <img :src="skuImageList[defaultImgIndex]?.imgUrl" ref="bigImg" />
        </div>
        <div class="mask" ref="mask"></div>
    </div>
</template>

<script>
export default {
    name: "Zoom",
    props: ["skuImageList"],
    data() {
        return {
            defaultImgIndex: 0,
        };
    },
    mounted() {
        this.$bus.$on("defaultImg", (index) => {
            this.defaultImgIndex = index;
        });
    },
    methods: {
        mousemove(e) {
            const event = this.$refs.event;
            const mask = this.$refs.mask;
            const bigImg = this.$refs.bigImg;
            const mouseOffset = {
                x: e.offsetX,
                y: e.offsetY,
            };
            const maskHalf = {
                x: this.$refs.mask.offsetWidth / 2,
                y: this.$refs.mask.offsetHeight / 2,
            };
            const maskLocation = {
                x: mouseOffset.x - maskHalf.x,
                y: mouseOffset.y - maskHalf.y,
            };

            if (maskLocation.x < 0) {
                maskLocation.x = 0;
            } else if (maskLocation.x > event.clientWidth - mask.offsetWidth) {
                maskLocation.x = event.clientWidth - mask.offsetWidth;
            }

            if (maskLocation.y < 0) {
                maskLocation.y = 0;
            } else if (maskLocation.y > event.clientHeight - mask.offsetHeight) {
                maskLocation.y = event.clientHeight - mask.offsetHeight;
            }

            mask.style.left = maskLocation.x + "px";
            mask.style.top = maskLocation.y + "px";

            bigImg.style.left = -maskLocation.x * 2 + "px";
            bigImg.style.top = -maskLocation.y * 2 + "px";
        },
    },
};
</script>

<style lang="less">
.spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
        width: 100%;
        height: 100%;
    }

    .event {
        width: 100%;
        height: 100%;
        position: absolute;
        top: 0;
        left: 0;
        z-index: 998;
    }

    .mask {
        width: 50%;
        height: 50%;
        background-color: rgba(0, 255, 0, 0.3);
        position: absolute;
        left: 0;
        top: 0;
        display: none;
    }

    .big {
        width: 100%;
        height: 100%;
        position: absolute;
        top: -1px;
        left: 100%;
        border: 1px solid #aaa;
        overflow: hidden;
        z-index: 998;
        display: none;
        background: white;

        img {
            width: 200%;
            max-width: 200%;
            height: 200%;
            position: absolute;
            left: 0;
            top: 0;
        }
    }

    .event:hover ~ .mask,
    .event:hover ~ .big {
        display: block;
    }
}
</style>
